I. Field of the Invention
The present invention relates to fluid control systems and, more particularly, to a fuel control system for an internal combustion engine.
II. Description of the Prior Art
In spark-ignition internal combustion engines, such as aircraft piston engines, the engine is normally supplied with a charge of fuel through either carburetion or fuel injection so that the charge of fuel, when mixed with the induction air charge, provides a combustible mixture to the engine combustion chambers or cylinders. The quantity of the fuel supplied to the engine can be regulated by a number of different means.
In most present aircraft piston engines, however, the fuel system may be manually controlled by means of a mixture control lever. This lever is operated by the pilot to provide leaner fuel mixtures to the engine for improved fuel economy and also to avoid excessively rich mixtures at higher altitudes. Such excessively rich mixtures can result in inconsistent engine combustion and even stalling of the engine.
Normally the mixture control lever of the aircraft is operated by the pilot in response to one or more predetermined engine operating parameters such as the exhaust gas temperature (EGT), the cylinder head temperature (CHT), the fuel flow rate, the altitude, the engine speed and/or the manifold pressure. Consequently, the control and adjustment of the mixture control lever by the pilot unduly increases the pilot workload and at the same time can result in an improper fuel mixture to the engine. An improper fuel mixture to the engine can result not only in excessive fuel consumption but also in engine damage from excessive cylinder head temperature.